The present invention relates to a guide plate for actuating a poppet valve.
Guide plates can be used to vary the motion characteristics of poppet valves that are used in internal combustion engines or pumps. The guide plate, which typically incorporates a guide path, can be moved such that a valve actuating means achieves different motion characteristics depending on the position of the guide plate. This is useful, as the valve actuation means then opens and closes the valve with different valve timing and/or valve movement depending on variables such as the speed of the piston.
It is a requirement of spark ignition engines to be throttled by controlled restriction of the air flow to the cylinders. In a predominance of engines a single butterfly valve, located at a distance from the inlet valves, is employed to reduce air flow by restricting air flow along the inlet tract, thus the lowering of the inlet tract pressure.
It is generally accepted that superior engine efficiency at part loads would result when full inlet tract pressure is maintained at all times. This situation is possible and optimal when throttling is achieved by a controlled variation of inlet valve opening.
It has also been demonstrated that in the case of multi-cylinder engines, the necessity for part load operation of individual cylinders can be minimized by the shutting down of a selected number of cylinders.
The present invention seeks to solve the problems associated with the prior art by providing a guide plate having a guide path for a valve actuation means, wherein part of the guide path is adapted to restrict the valve actuation means from moving the valve from an open position to a closed position, or from a closed position to an open position.
This provides the advantage that the mechanism for varying the valve timing and/or valve movement can also cause the valves to be held in a substantially shut position, or a substantially open position, for a full cycle of the piston. This allows the cylinder to be kept shut or open, thus preventing the cylinder from working and can also be used to regulate the speed of the engine.
In one embodiment, the present invention includes a guide plate having a guide path such that when the valve actuation member moves along a first portion of the guide path, the valve actuation means does not move the valve from a closed position to an open position, or from an open position to a closed position, and when the valve actuation member moves along a second portion of the guide path, the valve actuation means moves the valve from a closed position to an open position, or from an open position to a closed position.
In another form the present invention relates to a guide plate having a guide path including a valve actuating portion and a non-valve actuating portion, a valve actuating member which moves along the guide path, wherein the valve actuating member may move solely along the non-valve actuating portion such that the valve is not actuated.
In a further embodiment, the guide plate is moved to change the portion of the guide path along which the valve actuation member travels. In this way, the valve actuation member can move in a constant manner with respect to the cylinder position, but the valve lift can be varied by the movement of the guide plate. The guide plate can be moved to such a position that there is either no valve lift during a full cycle of movement of the piston within the cylinder, or to such a position that the valve lift is never zero, i.e., the valve does not close for a whole cycle of the piston movement within the cylinder.
The present invention also relates to a method of selectively activating or deactivating a valve for a mechanism having a guide plate with a guide path, and a valve actuation member moving along the guide path, including the steps of:
having a guide plate with a non-valve actuating portion and a valve actuating portion;
selectively positioning the guide plate in a position such that the valve actuation member moves along the guide path only along the non-valve actuation portion of the guide path so that the valve is not activated; and
positioning the guide plate such that the valve actuation member moves along at least a portion of the valve actuating portion to activate the valve.